MILPORT - APR 1
MILPORT - Aircraft Performance
MILPORT - Aircraft Performance
Kartei Details
| Karten | 57 |
|---|---|
| Sprache | English |
| Kategorie | Verkehrskunde |
| Stufe | Andere |
| Erstellt / Aktualisiert | 12.09.2016 / 16.01.2023 |
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Define the following features of the F404-GE-402 engine:
- type
- compressor
- bypass ratio
- turbine
- overall pressure ratio
type: afterburning turbofan
compressor: axial compressor with 3 fan and 7 compressor stages
bypass ratio: 0.34:1
turbine: 1 low-pressure and 1 high-pressure stage
overall pressure ratio: 26:1
Explain the general principle of a turboprop engine.
air is drawn into intake and compressed by compressor - in combustion chamber fuel is added and fuel-air mixture combusts - hot combustion gases expand through turbine - turbine drives partly the compressor and mainly transmitts the power through a reduction gearbox to the probeller - some of the gases expand through nozzle (only minor part of propulsion)
Name the basic components of a turboprob engine. (5)
- intake
- compressor
- combustor
- turbine
- propelling nozzle
Where are turboprop engines generally used?
small subsonic aircraft (PC7, PC9, PC21)
What is the gearbox for?
To reduce the RPM from the turbine for the propeller.
The propeller is normally a .....? type.
constant speed (variable pitch)
Where are turboprops mostly used? (for what requirements)
where high-performance short-takeoff and landing (STOL) capability and efficiency at modest flight speeds are required
What's the difference between turboprop and turbo shaft engines?
turboprop: gearbox is part of the engine
turbo shaft: (helicopters) gearbox is remote from engine
While most modern turbojet and turbofan engines use axial-flow compressors, turboprop engines usually contain at least one stage of ......? compression.
centrifugal
What can be used to increase the efficiency of propellers?
alter the pitch (adjusting it to the airspeed)
What can altering pitch of a propeller be used for additionally?
- to generate negative thrust (while decelerating on the runway)
- feathering (minimizing drag of a non-functioning propeller)
What's the purpose of an afterburner?
to provide a temporary increase in thrust, for:
- supersonic flight
- take-off
- combat situations
How does an afterburner work?
Injecting additional fuel into the jet pipe downstream of the turbine.
What's the advantage and disadvantage of an afterburner?
advantage: significantly increased thrust
disadvantage: very high fuel consumption and inefficiency
When are engines considered to be wet/dry? What is military/maximum power?
operating wet = afterburning is used
operating dry = no afterburning
engine producing maximum thrust wet = maximum power
engine producing maximum thrust dry = military power
Name 3 types of engines.
TURBO JET
TURBO FAN
TURBO PROP
Tuorbojets consist of which 5 components?
air inlet
air compressor
combustion chamber
gas turbine
nozzle
How does a turbojet engine work?
Compressor compresses air into the combustion chamber, there it is heated and expanded by the fuel combustion and expands out through the turbine into the nozzle, where it gets accelerated to high speed to provide propulsion.
What's the turbine doing?
driving the air compressor
Name 2 disadvantages of a turbojet engine.
inefficient (if flown below about Mach 2) and very noisy
Turbojets are still very common in ....... due to their ....., ..... and .....
medium range cruise missiles
high exhaust speed, low frontal area, relative simplicity
What are the stators doing?
air inlet: guiding the airlow of the compressed gases
The air intake (or inlet) is designed to be as efficient as possible at ..... ?
recovering the ram pressure of the air stream tube approaching the intake
What does the compressor do?
rotates at very high speed, adding energy to the airflow and at the same time squeezing (compressing) it into smaller space
-> pressure and temperature of the air rise
What is bleed air extracted for from the compressor in most turbojet aircraft? (3)
- air conditioning/pressurization
- engine inlet anti-icing
- turbine cooling
Name 4 types of compressor used in turbojets and gas turbines.
- axial
- centrifugal
- axial-centrifugal
- double-centrifugal
After leaving the compressor section, the compressed air enters the ...... ?
combustion chamber
Combustion chamber: as the mixture burns its temperature ..... dramatically, but the perssure actually ..... a few percent.
increases / decreases
Turbine: some shaft power is extracted for what reason?
to drive accessories like fuel, oil and hydraulic pump
In a turbojet almost ... (how much) of all the power generated by burning fuel is used by the compressor to compress the air for the engine?
2/3 --> inefficient
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